It's easier to find digital copies of the TSM than it is the actual books. Ebay usually has them and I believe IE use to sell some as well.
I prefer the actual book, since it's easier to bring outside with you. I went through mine and tore out every page (book was already broke in half) and put every single page in a sheet protector and in binders (took 3 3" binders just to get the big book and no telling how many sheet protectors). It should extend it's life quite a bit.